|
%I #31 Sep 08 2022 08:45:39
%S 10,13,16,18,19,22,23,25,28,30,31,33,34,37,38,40,43,44,46,48,49,51,52,
%T 53,55,58,61,63,64,65,66,67,68,70,72,73,76,77,78,79,82,83,85,86,88,90,
%U 91,93,94,97,98,99,100,103,106,107,108,109,110,112,113,114
%N Numbers k such that 2*k-11 is not a prime.
%C The terms are the values of 2*h*k + k + h + 6, where h and k are positive integers. - _Vincenzo Librandi_, Jan 19 2013
%H Vincenzo Librandi, <a href="/A153045/b153045.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = 5+A104275(n+1). [_R. J. Mathar_, Oct 22 2009]
%t Select[Range[10,200], !PrimeQ[2*#-11]&] (* _Vladimir Joseph Stephan Orlovsky_, Feb 09 2012 *)
%o (Magma) [n: n in [7..120] | not IsPrime(2*n - 11)]; // _Vincenzo Librandi_, Oct 11 2012
%o (Python)
%o from sympy import isprime
%o def ok(n): return n > 6 and not isprime(2*n-11)
%o print(list(filter(ok, range(115)))) # _Michael S. Branicky_, Oct 13 2021
%Y Cf. A097338, A153043, A163652, A104275.
%K nonn,easy
%O 1,1
%A _Vincenzo Librandi_, Dec 17 2008
|
